Mems diaphragm

ABSTRACT

A microelectromechanical system (MEMS) diaphragm is provided. The MEMS diaphragm includes a first conductive layer, a second conductive layer and a first dielectric layer. The first conductive layer is disposed on a substrate and having a plurality of openings. The openings have the same dimension, and the distance between the adjacent openings is gradually increased toward the edge of the first conductive layer. The second conductive layer is disposed between the first conductive layer and the substrate. The first dielectric layer is partially disposed between the first conductive layer and the second conductive layer, so that a portion of the first conductive layer is suspended.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of and claims the prioritybenefit of an U.S. application Ser. No. 12/248,631, filed on Oct. 9,2008, now allowed. The entirety of the above-mentioned patentapplication is hereby incorporated by reference herein and made a partof this specification.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a semiconductor device, and moregenerally to a MEMS diaphragm.

2. Description of Related Art

Micro-electromechanical system (MEMS) devices are mini-electromechanicaldevices, and the manufacturing technology thereof is similar to that ofintegrated circuits. With the rapid development of the electronicindustry and the manufacturing technology of integrated circuits, theMEMS devices fabricated based on the MEMS technology are varied andinclude tiny electromechanical devices such as accelerometers, switches,capacitors, sensors and diaphragms. The MEMS devices are widelyapplicable to electronic products due to the advantages of light weight,small size and excellent quality. For example, the MEMS diaphragmsfabricated based on the MEMS technology have become the mainstream inthe mini-microphone market, and are applicable to cell phones, digitalcameras, cordless headsets, laptops, hearing aids and electronic ears.

Generally speaking, a MEMS diaphragm includes a bottom electrode, a topelectrode partially suspended above the bottom electrode, and adielectric layer between the top and bottom electrodes. In the processof fabricating the MEMS diaphragm, after a bottom electrode, adielectric material layer and a top electrode having openings aresequentially formed on a substrate, a portion of the dielectric materiallayer is removed by the etchant such as hydrofluoric acid through theopenings in the top electrode, so that a dielectric layer is formedbetween the top and bottom electrodes. Accordingly, the top electrode issuspended above the bottom electrode and having the vibration property.For example, when the top electrode is vibrated by sound waves, thecapacitance between the top and bottom electrodes is changed, and thesound waves are converted to electric signals by the MEMS diaphragm.

However, during the step of removing the portion of the dielectricmaterial layer, the etchant may over-etch the dielectric material layerand even damage the electronic devices around the MEMS diaphragm.Therefore, the device characteristics of the MEMS diaphragms andelectronic devices are affected.

SUMMARY OF THE INVENTION

The present invention provides a MEMS diaphragm including a firstconductive layer, a second conductive layer and a first dielectriclayer. The first conductive layer is disposed on a substrate and havinga plurality of openings. The openings have the same dimension, and thedistance between the adjacent openings is gradually increased toward theedge of the first conductive layer. The second conductive layer isdisposed between the first conductive layer and the substrate. The firstdielectric layer is partially disposed between the first conductivelayer and the second conductive layer, so that a portion of the firstconductive layer is suspended.

According to an embodiment of the present invention, the firstconductive layer is shaped as a mesh, for example.

According to an embodiment of the present invention, the firstconductive layer includes a plurality of patterns and the openings aredisposed between the patterns.

According to an embodiment of the present invention, each patternincludes a winding conductive line.

According to an embodiment of the present invention, the dimensions ofthe winding conductive lines are the same or different.

According to an embodiment of the present invention, the MEMS diaphragmfurther includes a second dielectric layer. The second dielectric layeris at least partially disposed between the second conductive layer andthe substrate, so that a portion of the second conductive layer issuspended.

According to an embodiment of the present invention, the distancesinclude a plurality of first distances and a plurality of seconddistances greater than the first distances. Each of the first distancesis at a position apart from the edge of the first conductive layer by adistance smaller than a certain value, and each of the second distancesis at a position apart from the edge of the first conductive layer by adistance greater than the certain value.

In the present invention, the first conductive layer of the MEMSdiaphragm has openings with different dimensions. The dimensions of theopenings are gradually reduced toward the edge of the first conductivelayer, or the dimensions having a first dimension and the openingshaving a second dimension are arranged alternately. It is noted that inthe process of fabricating the MEMS diaphragm, the configuration of theopenings can avoid over-etching of the dielectric material layer of theMEMS diaphragm and prevent the electronic device around the MEMSdiaphragm from being damaged. Therefore, the desired devicecharacteristics of the MEMS diaphragm and the adjacent electronic devicecan be achieved.

In order to make the aforementioned and other objects, features andadvantages of the present invention comprehensible, a preferredembodiment accompanied with figures is described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1A schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a first embodiment of the present invention.

FIG. 1B schematically illustrates a local top view of the MEMS diaphragmin FIG. 1A.

FIG. 2A schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a second embodiment of the present invention.

FIG. 2B schematically illustrates a local top view of the MEMS diaphragmin FIG. 2A.

FIG. 3A schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a third embodiment of the present invention.

FIG. 3B schematically illustrates a top view of each pattern 112 of theMEMS diaphragm in FIG. 3A.

FIG. 4A schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a fourth embodiment of the present invention.

FIG. 4B schematically illustrates a local top view of the MEMS diaphragmin FIG. 4A.

FIG. 5 schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a fifth embodiment of the present invention.

FIG. 6 schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a sixth embodiment of the present invention.

FIG. 7 schematically illustrates a local top view of a MEMS diaphragmaccording to a seventh embodiment of the present invention.

FIG. 8 schematically illustrates a cross-sectional view of a MEMSdiaphragm according to an eighth embodiment of the present invention.

FIG. 9 schematically illustrates a local top view of a MEMS diaphragmaccording to a ninth embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

FIG. 1A schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a first embodiment of the present invention. FIG.1B schematically illustrates a local top view of the MEMS diaphragm inFIG. 1A.

Referring to FIGS. 1A and 1B, a MESM diaphragm 10 and an electronicdevice 20 are respectively disposed in the adjacent regions of asubstrate 100. The MEMS diaphragm 10 includes a first conductive layer110, a second conductive layer 120, a dielectric layer 130 and adielectric layer 140. The first conductive layer 110 is disposed on thesubstrate 100. The first conductive layer 110 has a plurality ofopenings S. The dimensions of the openings S are A1, A2, A3, A1′, A2′and A3′, which are gradually reduced toward the edge P of the firstconductive layer 110. That is, A1<A2<A3 and A1′<A2′<A3′. This embodimentis exemplified, but not limited to, by that A1 is equal to A1′, A2 isequal to A2′, and A3 is equal to A3′. In this embodiment, the firstconductive layer 110 is shaped as a mesh, for example. The firstconductive layer 110 includes a conductive material such as polysilicon,polycide, aluminum, tungsten, titanium or copper. The second conductivelayer 120 is disposed between the first conductive layer 110 and thesubstrate 100. The second conductive layer 120 includes a conductivematerial such as polysilicon, polycide, aluminum, tungsten, titanium orcopper. In this embodiment, the second conductive layer 120 is a wholepiece of the conductive layer, for example. In another embodiment (notshown), the second conductive layer 120 can be shaped as a mesh or othershapes.

In this embodiment, the dielectric layer 130 is partially disposedbetween the first conductive layer 110 and the second conductive layer120, so that a portion the first conductive layer 110 is suspended. Thedielectric layer 140 is disposed between the second conductive layer 120and the substrate 100. In another embodiment (not shown), the dielectriclayer 140 can be partially disposed between the second conductive layer120 and the substrate 100, so that a portion the second conductive layer120 is suspended above the substrate 100. The dielectric layers 130 and140 respectively include a dielectric material such as silicon oxide,un-doped silicon glass (USG), borophosphosilicate glass (BPSG) orphosphosilicate glass (PSG).

In this embodiment, the electronic device 20 may be a complementarymetal-oxide-semiconductor (CMOS) device and disposed around the MEMSdiaphragm 10. In other words, the edge P of the MEMS diaphragm 10 isadjacent to the electronic device 20. The electronic device 20 includesa gate 202 disposed on the substrate 100, an interconnection layer 204electronically connected to the gate 202, a dielectric layer 206 and adielectric layer 208. The dielectric layer 206 is disposed between thegate 202 and the interconnection layer 204. The dielectric layer 208 isdisposed between the gate 202 and the substrate 100. The material of thedielectric layers 206 and 208 may be the same as that of the dielectriclayers 130 and 140. The dielectric layer 208 includes silicon oxide, andthe dielectric layer 206 includes a dielectric material such as siliconoxide, USG, BPSG or PSG, for example.

Generally speaking, in the process of fabricating the MEMS diaphragm 10,after a second conductive layer 120, a dielectric material layer (notshown) and a first conductive layer 110 are sequentially formed on thesubstrate 100, a potion of the dielectric material layer is removed bythe ethant such as hydrofluoric acid through the openings S in the firstconductive layer 110, so as to form a dielectric layer 130 partiallydisposed between the first conductive layer 110 and the secondconductive layer 120, and thus, a portion of the first conductive layer110 is suspended. In this embodiment, the dimensions of the openings Sare gradually reduced toward the edge P of the first conductive layer110, so as to effectively avoid over-etching of the dielectric materiallayer as well as etching of the dielectric layer 206 of the electronicdevice 20 when the etchant is used. In other words, the configuration ofthe openings in the first conductive layer can prevent the MEMSdiaphragm and the adjacent electronic device from being damaged by theetchant, so that the desired device characteristics of the MEMSdiaphragm and the electronic device can be achieved. Further, themembrane stress of the first conductive layer can be increased by thedimension change of the openings in the first conductive layers, so asto enhance the device characteristics of the MEMS diaphragm.

Second Embodiment

FIG. 2A schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a second embodiment of the present invention.FIG. 2B schematically illustrates a local top view of the MEMS diaphragmin FIG. 2A. The structure of the MEMS diaphragm 10 a in the secondembodiment is similar to that of the MEMS structure diaphragm 10 in thefirst embodiment, and the difference is illustrated in the following.

Referring to FIGS. 2A and 2B, the first conductive layer 110 includes aplurality of patterns 112 and a plurality of openings S between thepatterns 112. The dimensions of the openings S are A1, A2, A3, A1′, A2′and A3′, which are gradually reduced toward the edge P of the firstconductive layer 110. That is, A1<A2 <A3 and A1′<A2′<A3′. Thisembodiment is exemplified, but not limited to, by that A1 is equal toA1′, A2 is equal to A2′, and A3 is equal to A3′. It is noted that thisembodiment in which each pattern 112 is shaped as a stripe is providedfor illustration purposes and is not to be construed as limiting thepresent invention. In another embodiment (not shown), the patterns 112can have other shapes.

Third Embodiment

FIG. 3A schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a third embodiment of the present invention. FIG.3B schematically illustrates a top view of each pattern 112 of the MEMSdiaphragm in FIG. 3A. The structure of the MEMS diaphragm 10 b in thethird embodiment is similar to that of the MEMS structure diaphragm 10in the first embodiment, and the difference is illustrated in thefollowing.

Referring to FIGS. 3A and 3B, the first conductive layer 110 includes aplurality of patterns 112 arranged in array and a plurality of openingsS between the patterns 112. The dimensions of the openings S are A1, A2,A3, A1′, A2′ and A3′, which are gradually reduced toward the edge P ofthe first conductive layer 110. That is, A1<A2<A3 and A1′<A2′<A3′. Thisembodiment is exemplified, but not limited to, by that A1 is equal toA1′, A2 is equal to A2′, and A3 is equal to A3′. Further, each pattern112 includes a winding conductive line 114 and an opening T. Thisembodiment in which the line width W of the conductive line 114 and thedimension of the opening T are fixed in each pattern 112 is provided forillustration purposes, and is not to be construed as limiting thepresent invention. In details, the dimension of the opening T can bechanged as the line width W of the conductive line 114 is changed. Forexample, when the total area occupied by the conductive line 114 and theopening T is constant, the dimension of the opening T is getting smalleras the line width W of the conductive line 114 is getting larger, andvice versa. Accordingly, the membrane stress of the first conductivelayer can be further adjusted to enhance the device characteristics ofthe MEMS diaphragm. This embodiment in which the dimensions of thepatterns 112 are the same is provided for illustration purposes, and isnot to be construed as limiting the present invention. It is appreciatedby persons skilled in the art that the dimensions of the patterns 112can be different upon the design requirement.

Fourth Embodiment

FIG. 4A schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a fourth embodiment of the present invention.FIG. 4B schematically illustrates a local top view of the MEMS diaphragmin FIG. 4A. The structure of the MEMS diaphragm 10 c in the fourthembodiment is similar to that of the MEMS structure diaphragm 10 in thefirst embodiment, and the difference is illustrated in the following.

Referring to FIGS. 4A and 4B, the first conductive layer 110 includes aplurality of openings S. The openings S having a first dimension A1 andthe openings S having a second dimension A2 are arranged alternately,and the first dimension A1 is not equal to the second dimension A2. Indetails, the dimensions of openings S are sequentially A1, A2, A1, A2,A1, A2 . . . counting form the edge P of the first conductive layer 110.In this embodiment, the first dimension A1 is smaller than the seconddimension A2, for example. In another embodiment (not shown), the firstdimension A1 can be greater than the second dimension A2. It is notedthat this embodiment in which the openings have two dimensions isprovided for illustration purposes and is not to be construed aslimiting the present invention. In another embodiment (not shown), theopenings can have more than two dimensions. For example, the dimensionsof openings S are sequentially A1, A2, A3, A1, A2, A3 . . . or A1, A2,A3, A4, A1, A2, A3, A4 . . . counting form the edge of the firstconductive layer. Further, the dimensions of the openings can be notcompletely the same. For example, the dimensions of openings S aresequentially A2, A2, A1′, A2′, A1″, A2″ A1, A2, A1′, A2′, A1′, A2″ . . .counting form the edge of the first conductive layer, wherein A1<A2,A1′<A2′ and A1″<A2″.

In this embodiment, the openings having a small dimension and theopenings having a large dimension are arranged alternately, so as tocontrol the flow rate and flow volume of the etchant entering thedielectric material layer through the openings. Therefore, when theetchant is used, over-etching of the dielectric material layer at theedge P as well as etching of the dielectric layer 206 of the electronicdevice 20 can be effectively avoided. In other words, the configurationof the openings in the first conductive layer can prevent the MEMSdiaphragm and the adjacent electronic device from being damaged by theetchant, so as to achieve the desired device characteristics of the MEMSdiaphragm and the electronic device. Further, the membrane stress of thefirst conductive layer can be increased by the dimension change of theopenings in the first conductive layers, so as to enhance the devicecharacteristics of the MEMS diaphragm.

Fifth Embodiment

FIG. 5 schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a fifth embodiment of the present invention. Thestructure of the MEMS diaphragm 10 d in the fifth embodiment is similarto that of the MEMS structure diaphragm 10 c in the fourth embodiment,and the difference is illustrated in the following.

Referring to FIG. 5, the first conductive layer 110 includes a pluralityof patterns 112 and a plurality of openings S between the patterns 112.The openings S having a first dimension A1 and the openings S having asecond dimension A2 are arranged alternately, and the first dimension A1is not equal to the second dimension A2. In details, the dimensions ofthe openings S are subsequently A1, A2, A1, A2, A1, A2 . . . countingfrom the edge P of the first conductive layer 110. It is noted that thisembodiment in which the openings have two dimensions is provided forillustration purposes and is not to be construed as limiting the presentinvention. In another embodiment (not shown), the openings can have morethan two dimensions, and the possible configurations of the openings arementioned in the fourth embodiment; thus, the details are not iterated.Further, each pattern 112 can be shaped as a stripe (FIG. 2B), a windingline (FIG. 3B) or other shapes, which are mentioned in the second andthird embodiments, and thus the details are not iterated.

Sixth Embodiment

FIG. 6 schematically illustrates a cross-sectional view of a MEMSdiaphragm according to a sixth embodiment of the present invention. Thestructure of the MEMS diaphragm 10 e in the sixth embodiment is similarto that of the MEMS structure diaphragm 10 a in the second embodiment,and the difference is illustrated in the following.

Referring to FIG. 6, the first conductive layer 110 includes a pluralityof patterns 112 and a plurality of openings S between the patterns 112.In this embodiment, the openings S have two dimensions A1 and A2, andA1<A2. When the distance between an opening S and the edge P of thefirst conductive layer 110 is smaller than a certain value d, thedimension of the opening S is A1. When the distance between an opening Sand the edge P of the first conductive layer 110 is greater than thecertain value d, the dimension of the opening S is A2. In other words, agroup of the openings S closer to the edge P of the first conductivelayer 110 have a smaller dimension, but another group of the openings Saway from the edge P of the first conductive layer 110 have a largerdimension. This embodiment in which the openings have two dimensions isprovided for illustration purposes and is not to be construed aslimiting the present invention. In another embodiment (not shown), theopenings can be divided into a plurality of groups, and the dimensionsof groups of openings are gradually reduced toward the edge of the firstconductive layer. Further, each pattern 112 can be shaped as a stripe(FIG. 2B), a winding line (FIG. 3B) or other shapes, which are mentionedin the second and third embodiments, and thus the details are notiterated.

Seventh Embodiment

FIG. 7 schematically illustrates a local top view of a MEMS diaphragmaccording to a seventh embodiment of the present invention. Thestructure of the MEMS diaphragm 10 f in the seventh embodiment issimilar to that of the MEMS structure diaphragm 10 in the firstembodiment, and the difference is illustrated in the following.

Referring to FIG. 7, in this embodiment, the openings S have twodimensions A1 and A2, and A1<A2. When the distance between an opening Sand the edge P of the first conductive layer 110 is smaller than acertain value d, the dimension of the opening S is A1. When the distancebetween an opening S and the edge P of the first conductive layer 110 isgreater than the certain value d, the dimension of the opening S is A2.In other words, a group of the openings S closer to the edge P of thefirst conductive layer 110 have a smaller dimension, but another groupof the openings S away from the edge P of the first conductive layer 110have a larger dimension. This embodiment in which the openings have twodimensions is provided for illustration purposes and is not to beconstrued as limiting the present invention. In another embodiment (notshown), the openings can be divided into a plurality of groups, and thedimensions of groups of openings are gradually reduced toward the edgeof the first conductive layer.

Eighth Embodiment

FIG. 8 schematically illustrates a cross-sectional view of a MEMSdiaphragm according to an eighth embodiment of the present invention.The structure of the MEMS diaphragm 10 g in the eighth embodiment issimilar to that of the MEMS structure diaphragm 10 a in the secondembodiment, and the difference is illustrated in the following.

Referring to FIG. 8, the first conductive layer 110 includes a pluralityof patterns 112 and a plurality of openings S between the patterns 112.In this embodiment, the openings S have the same dimension Al. Thedimensions of the patterns 112 are B1, B2, B3 and B4, which aregradually increased toward the edge P of the first conductive layer 110.That is, B1>B2>B3>B4. In another embodiment (not shown), the patterns112 have two dimensions B1 and B2, and B1>B2. When the distance betweena pattern 112 and the edge P of the first conductive layer 110 issmaller than a certain value d, the dimension of the pattern 112 is B1.When the distance between a pattern 112 and the edge P of the firstconductive layer 110 is greater than the certain value d, the dimensionof the pattern 112 is B2. Further, each pattern 112 can be shaped as astripe (FIG. 2B), a winding line (FIG. 3B) or other shapes, which arementioned in the second and third embodiments, and thus the details arenot iterated.

Ninth Embodiment

FIG. 9 schematically illustrates a local top view of a MEMS diaphragmaccording to a ninth embodiment of the present invention. The structureof the MEMS diaphragm 10 h in the seventh embodiment is similar to thatof the MEMS structure diaphragm 10 in the first embodiment, and thedifference is illustrated in the following.

Referring to FIG. 9, in this embodiment, the openings S have the samedimension A1. The distance 116 between the adjacent openings S isgradually increased toward the edge P of the first conductive layer 110;that is, B1>B2>B3>B4. In another embodiment (not shown), the distances116 have two values B1 and B2, and B1>B2. When a distance 116 is at aposition apart from the edge P of the first conductive layer 110 by adistance smaller than a certain value d, the distance 116 is B2. When adistance 116 is at a position apart from the edge P of the firstconductive layer 110 by a distance greater than the certain value d, thedistance 116 is B2.

In another embodiment, it is noted that the MEMS diaphragm includes aplurality of sub-units, and each of the sub-units can be the smallestunit for forming the MEMS diaphragm. Each of the sub-units includes theabove-mentioned openings or patterns.

In summary, the first conductive layer of the MEMS diaphragm of thepresent invention has openings with different dimensions. The dimensionsof the openings are gradually reduced toward the edge of the firstconductive layer, or the dimensions having a small dimension and theopenings having a large dimension are arranged alternately. Theconfiguration of the openings can avoid over-etching of the dielectricmaterial layer of the MEMS diaphragm and prevent the electronic devicearound the MEMS diaphragm from being damaged. Further, the membranestress of the first conductive layer can be increased by the dimensionchange of the openings in the first conductive layer, so as to furtherenhance the device characteristics of the MEMS diaphragm. Therefore, thedesired device characteristics of the MEMS diaphragm and the adjacentelectronic device can be achieved.

This invention has been disclosed above in the preferred embodiments,but is not limited to those. It is known to persons skilled in the artthat some modifications and innovations may be made without departingfrom the spirit and scope of this invention. Hence, the scope of thisinvention should be defined by the following claims.

1. A MEMS diaphragm, comprising: a first conductive layer, disposed on asubstrate and having a plurality of openings, wherein the openings havethe same dimension, and a distance between the adjacent openings isgradually increased toward an edge of the first conductive layer; asecond conductive layer, disposed between the first conductive layer andthe substrate; and a first dielectric layer, partially disposed betweenthe first conductive layer and the second conductive layer, so that aportion of the first conductive layer is suspended.
 2. The MEMSdiaphragm of claim 1, wherein the first conductive layer is shaped as amesh.
 3. The MEMS diaphragm of claim 1, wherein the first conductivelayer comprises a plurality of patterns and the openings are disposedbetween the patterns.
 4. The MEMS diaphragm of claim 3, wherein eachpattern comprises a winding conductive line.
 5. The MEMS diaphragm ofclaim 4, wherein dimensions of the winding conductive lines are the sameor different.
 6. The MEMS diaphragm of claim 1, further comprising asecond dielectric layer, at least partially disposed between the secondconductive layer and the substrate, so that a portion of the secondconductive layer is suspended.
 7. The MEMS diaphragm of claim 1, whereinthe distances comprise a plurality of first distances and a plurality ofsecond distances smaller than the first distances, each of the firstdistances is at a position apart from the edge of the first conductivelayer by a distance smaller than a certain value, and each of the seconddistances is at a position apart from the edge of the first conductivelayer by a distance greater than the certain value.